Rotary drier



Dec. 11, 1951 c. E. BILL ROTARY DRIER Filed March 21, 1950 INVENTOR:CLIFFORD E. BILL.

ATT'YS Patented Dec. 11, 1951 ROTARY DRIER Clifford E. Bill, Louisville,Ky., assignor to General American Transportation Corporation, Chicago,111., a corporation of New York Application March 21, 1950, Serial No.150,909

3 Claims.

ing, particularly in the case of direct fire dryerswhere the hot air andgases employed for drying purposes contact the materials directly.

The principal object of the present invention is to provide an improveddryer of a simple, compact and inexpensive form which may be operatedmore eificiently than those heretofore known and without damage to thematerials being dried. The present invention is preferably embodied in arotary dryer of the direct fire parallel flow type wherein the hot gasesand the materials to be dried move in the same direction through thedrying chamber and in direct contact with each other. By means of anovel form and. arrangement of lifting vanes, intercepting disks andbaffles in the chamber, the materials to be dried are caused to have amaximum intimate contact of the materials with the gases. The contact orretention time between the particles and the gases is decreased ascompared with former practice because a substantially higher velocity offlow of the gases is employed. An important feature is that thistremendous increase in the velocity of the hot gases in relation to thematerial flow gives a proportionately higher increase in dryer capacity.By reason of the more effective use of the hotgases, a more completerem'ovalj'of the water or other liquid from the materials is effected.These advantages lead to a further one in that it is possible to employa smaller dryer for a particular task, thereb ef fecting a saving incost and operation.

Because of the lowretention time for the materials in the dryer,.in thepractice of the present invention, the temperature of the dried productis comparatively low so that the requirements for cooling the productare less than formerly. These and other objects and advantages of theinvention will appear more fully hereinafter.

The nature of the invention will be understood from the followingspecification taken with the accompanying drawings in which oneembodiment is illustrated. In the drawings,

Figure 1 shows a side elevation of the improved rotary dryer andassociated parts with the upper part of the dryer shown in longitudinalsection and with some of the longitudinal lifting vanes removed;

Fig. 2 shows a vertical section taken on'the line 2-2 of Fig. 1;

Fig. 3 shows a sectional view taken on the line 33 of Fig. 1;

Fig. 4 shows a sectional view taken on the line 4-4 of Fig. 1;

Fig. 5 shows a sectional view taken on the line" 55 of Fig. 1; y 7 vFig. 6 shows a sectional view taken on the line 6-6 of Fig. 1; and

Fig. 7 shows a sectional view taken on the line" 1-1 of Fig. 1. I V

As illustrated in the drawing theinvention comprises a rotarycylindrical drumlfl formed of sheet metal and provided at the inlet endthereof with a transverse end wall Illa and, at the outlet end thereof,with a cone-shaped wall lob. This cylindrical drum is provided ,on itsouter side with two relatively fixed annular tires or bearing members.II which areadapted to be engaged by supporting rollers l2 mountedonbearing blocks l3 fixed uponthe fiooror other. support M. The blocks l3have rollers |3 a which. extend on opposite sidesof the associated tire.II to hold the rotary drum against endwise movement. The drum ispreferably mounted to rotate about a horizontal axis, as illustrated in,the drawings, and its rotation is effected through power applied to aring gear 15 which extends around and is secured to the wall of thedrumadjacent one of the tires II. This ring gear is attached to the wall ofthe drum through brackets l6 and an annular plate H, as shownparticularlyin Fig. 7, and the gear is actuated toretate the drumbyanendless chain l9 which e x= tendsdownwardly beneath the drumandmeshes with a driving pinion 20 fixed upon a shaft This. shaft isjournaled in a bearing Zi 'and is driven an electriclmotor 23. Thebearing 2?" and the motor are mounted upon a supporting block 24 whichis secured to the base 14. With this arrangement, the drum I0 isadaptedto be rotated at a suitable speed for agitating the materials inthe dryer and bringing them into con-- tact with the hot gases ofcombustion which are employed for drying purposes. j

The hot gases are supplied from a gas furnace 25 provided with a burner26 through which the liquid or gaseous fuel is introduced into thecornbustion chamber. This furnace is supported upon saddle members 21carried by the supporting blocks 28 which rest upon the base [4. The hotgases of combustion pass from the furnace chamber through the outletfiue 30 which has a relatively close fit with the walls of a centralopening formed in the end wall 1a of the rotary drum.

The materials to be dried are introduced into the drum. ID through thecentral opening in its end wall |a by means of a feed chute 32 which hasan upwardly directed inlet opening 32a and which has its lower partinclined downwardly and forwardly through the flue 38 to discharge at apoint located centrally of the rotary drum l8 9. short distance inwardlyfrom the plane of the end wall Illa.

The hot air and gases and the dried materials are withdrawn at thedischarge end of the drying drum l0 through the tapered portion 10bthereof and through a power driven centrifugal exhaust fanv 33-. which.is adapted to discharge the mixture. into asuitable settling chamberfrom: which the air and gases escape and from which the solid driedmaterials settle by gravity to a discharge opening at the bottom.

As apart of the means for agitating the materials to be dried andmaintaining. a sufficient turbulence thereof to bring them into intimatecontact with the hot drying gases, the cylindrical drum I8 is providedon its inner side with a plurality of spaced lifting vanes 35 whichextend radially and. which have their outer edges welded or otherwisesecured to the wall 1.. For a considerable distance, preferably aboutone-half of the length of the drum III, the vanes 35 are of equalradial. depth, as shown. in Figs. 1 and 4, and all parts of each vanelie in one plane. From. apoint adjacent the middle of the drum l0 to thedischarge end thereof,. the. vanes H] are increased in. radial depth asshown. at. 35a in Figs. 1 and 6.. some of the vanes 35 which have theshorter radial dimension have their inner edges bent at angles to theradial body portions thereof as sho n at 351) in Fig.. 5. Beyond themiddle point of the dryer where the radial vanes have an increaseddepth, an increased number of the vanes have their inner margins bent atangles to the body portions thereof as shown at 350 in Fig- 6. Thepurpose of angularity of the inner edges of some of the vanes is toenable these vanes more readily to pick up the materials being dried andto convey these materials around in the paths of. travel of the vanes sothey are dropped when the vanes reach or approach the upper parts oftheir paths. As the materials become dryer and perhaps more finelydivided, it is usually desira-ble to have an increased number of vanesprovided with. inclined inner edges as the dischar eend' of the dr ingdrum is approached.

The lifting vanes 35 are adapted to cooperate with a plurality ofradially extending sheetmetal.

rings 31 and a plurality of radially extending metal disks 38 which arearranged in pairs and spaced. apart. The rings 31 are slotted at theirouter margins. to receive the vanes 35 and their outer edges are weldedto the drum l0. Each ring 31 is provided with a central opening 31a and.these openings are preferably of the s me size throughout the length ofthe drum. Each ring 31 cooperates with an adjacent disk 38 which iscircular in form and. preferably of slightly larger diameter than theaperture 31a, in. the ring which is located on the: inlet side thereofso: that the gases and materials to be dried are compelled to follow atortuous path in moving Toward the middle of the drum Ill from the inletside of the ring 3'! to the outlet side of the associated disk 38. Thesedisks may be mounted as shown in Fig. 4 by a series of radiallyextending rods 39 which are securely attached to the outer part of thedisk 38 and which have their outer threaded extremities extendingthrough holes in the drum [0 where they are secured by nuts 40.

A considerable number of baflle rings 3'! and disks or targets 38 areembodied in the construction and distributed preferably in a uniformmanner throughout the length of the drying drum. Each ring 31 isassociated with one of the disks 38 and these members constitute a pairwhich are spaced substantially from another similar pair so that eachdisk is closer to the ring 3'! preceding it than it is to the next ringon the discharge side thereof. The distance between each disk 38 and thepreceding ring 31': may preferably be about one-third of the distancebetween two adjacent rings 3! measured longitudinally of the dryer. Forillustration, with a drumi'lfl which is. sixty feet long, the first ring31 is located six feet from the inlet end of the drum, is spaced twofeet from the disk 38 which is associated therewith on its dischargeside and is spaced six feet from the next following ring. In thisparticular embodiment, the drying drum EU has an internal diameter ofeight feet, the rings 31 have central openings which are four feet fiveinches in diameter and the disks 38 are five feet in diameter. Thesedimensions are given by way of illustration and not by way of limitationand are intended to indicate relative proportions which have been foundto give very satisfactory results in practice.

With the foregoing construction and arrangement of apparatus, thematerials to be dried are introduced more or less continuously throughthe feed chute 32 and they are drawn with the hot gases of combustionpassing through the flue 30 and then through the chamber of the dryingdrum l8 by the action of the centrifugal blower 33 which has its suctioninlet connected to the discharge end of the drying chamber. As the gasesand materials are drawn through the chamber, the drum is rotated at arelatively low speed, for example, 8 revolutions per minute, and, asthis rotation continues, the materials are carried around by the vanes35 and continually dropped as the vanes reach their uppermost positionwhile, at the same time, the current of hot air and gases causes thematerials to impinge upon the rings 31 and upon the disks 38. The gasesand materials must pass around disks 38 through the tortuous path whichis provided by the spaced rings and disks and the gases and materialsthen have an opportunity to lose momentum on the discharge side of. eachdisk 38 before they are accelerated again to contact with the nextfollowing ring 3i and disk 38. In this way the gases and materials arethoroughly intermingled with each other and are caused to move intortuous paths and with constantly changing velocities so that thematerials as well as the gases move both longitudinally and radially andin other directions in a manner adapted to bring about a thoroughmingling of the gases and particles to be dried even though the gasesand materials pass through the chamber of the drum H1 at. relativelyhigh speeds. As a consequence, very surprising results are obtained withrespect to the thoroughness of the drying of the materials and therapidity with which they are dried during the short time interval oftheir passage through the drying chamber.

To obtain the desired results, a relatively large number of the fiatrings 31 and the circular disks 38 should be employed, so that thematerials to be dried will be caused to follow a tortuous path alongwith the hot gases, thereby bringing about intimate and repeatedcontacts of all surfaces of each particle with the hot drying medium.The number of baflle rings and cooperating disks will depend upon thelength of the drying drum but desirable results may be obtained if thespacing of two successive rings is not greater than the diameter of thedrum. The results are improved by arranging the rings in pairs, that is,with each disk closer to the next preceding ring than it is to the nextfollowing ring. This spacing is preferably followed throughout thelength of the drum. It is believed that this spacing arrangement resultsin alternate increases and decreases in the velocity of the gases with aconsequent tendency for the materials to drop from the gas currentduring the periods of decreased velocity, thereby further increasing thegeneral turbulence and the intimate contact of the gases with theparticles. The closely spaced vanes, rings and disks have the furtheradvantage that they become heated by the passing hot gases and radiatetheir heat to the moving materials, thereby supplementing the directaction of the gases.

Although one form of the invention has been shown and described by Wayof illustration, it will be understood that it may be constructed invarious other embodiments which come within the scope of the appendedclaims.

I claim:

1. A rotary dryer comprising a rotatable cylindrical drum having inletand outlet openings, means for rotating said drum, means for introducinghot gases and materials to be dried through said inlet opening, meanscommunicating with said outlet opening for drawing said gases and saidmaterials through said drum, a series of longitudinally extendinglifting vanes attached to the inner surface of said drum and extendinginwardly therefrom, a plurality of flat radial rings attached to saiddrum and distributed throughout its length, and a plurality of diskseach located opposite the opening of one of said rings on the dischargeside thereof, said vanes increasing in radial depth toward the dischargeend of said drum.

2. A rotary dryer comprising a rotatable cylindrical drum having inletand outlet openings, means for rotating said drum, means for introducinghot gases and materials to be dried through said inlet opening, meanscommunicating with said outlet opening for drawing said gases and saidmaterials through said drum, a series of longitudinally extendinglifting vanes attached to the inner surface of said drum and extendinginwardly therefrom, a plurality of flat radial rings attached to saiddrum and distributed throughout its length, and a plurality of diskseach located opposite the opening of one of said rings on the dischargeside thereof, some of said vanes having their inner edges bent to formflanges directed at angles to radial planes, said flanges increasing innumber toward the discharge end of said drum.

3. A rotary dryer comprising a rotatable cylindrical drum having inletand outlet openings, means for rotating said drum, means for introducinghot gases and materials to be dried through said inlet opening, meanscommunicating with said outlet opening for drawing said gases and saidmaterials through said drum, a series of longitudinally extendinglifting vanes attached to the inner surface of said drum and extendinginwardly therefrom, a plurality of flat radial rings attached to saiddrum and distributed throughout its length, and a plurality of diskseach located opposite the opening of one of said rings on the dischargeside thereof, some of said vanes having their inner edges bent to formflanges directed at angles to radial planes, said flanges increasing innumber and said vanes increasing in radial depth toward the dischargeend of said drum.

CLIFFORD E. BILL.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,299,492 Mangelsdorf Apr. 8,1919 1,898,480 Corkill Feb. 21, 1933 2,096,049 Lissauer Oct. 19, 19372,341,101 Howard Feb. 8, 1944 FOREIGN PATENTS Number Country Date605,221 Great Britain July 19, 1948

